As the powder vessel such as said toner vessel, although of course not limited thereto, there has usually been used the one illustrated in FIG. 1, wherein a vessel body 1 is filled with powder 4 as shown in FIG. 3, thereafter an opening portion 3 of said vessel body is covered with a cover means 2, and one end 2' of said cover means 2 is bent upwards.
The opening means which has usually been used for stripping the cover means 2 and uncovering the powder vessel as mentioned above is illustrated at 15 in FIG. 2.
This opening means 15 comprises providing a flat handle 17 in a projecting manner at one end of a hollow tubular body 16 and further providing an axially extending slit 18 at a part of the body 16 on the side opposite to said handle 17. Upon uncovering the powder vessel using this opening means 15, the end 2' of the cover means 2 is inserted in the slit 18, and the opening means 15 is turned clockwisely in FIG. 3 with the handle 17. As the result of this, the cover means 2 is gradually wound around the body 16 of the opening means 15 and is uncovered.
However, the above vessel is defective in that since the body 1 is filled with powder 4 and thereafter its opening portion is wholly tightly closed with the cover means 2, the air within the vessel tends to expand as the temperature rises and the internal pressure increases, whereby at the first time of uncovering, a part 4' of the powder 4 spouts out of the vessel as shown in FIG. 3 and is scattered thereabout to cause environmental pollution.